MRC – Competence in high shear mixing technology
Tailor-made solutions to meet all of your individual stirring and shear mixing requirements. We offer you a complete solution consisting of stirrer and mixer units, mixing container, handling and discharge systems including safety and electrical technology.
Our technology centre is fitted out with a full range of machinery, and is always ready to develop solutions. All mixer and stirring units are available with comprehensive technical features and could be designed acc to requirements in different ATEX zones. We are able to provide you with full IQ / OQ documentation on request.
Planetary dissolver mixers have very versatile applications. Always the perfect mixing solution:
Planetary Dissolver Shear mixing
They have two separate drives, which allows the slow-moving planetary mixing tool to be operated independently of the high-speed dissolver.
Both rotational speeds are infinitely variable, therefore enabling the operator to define the mixture treatment. With the support of the dissolver, high shear forces can be applied to the product. The planetary stirring tool effectuates good mixing results even in high viscosity processes. In addition, a rotating wall scraper ensures the product remains in the centre of the container at all times during the mixing process.
Instead of a dissolver other high speed stirrers can, of course, be applied, such as pitched blade impellers. Often a pitched blade impeller is combined with a dissolver, which ensures flow in the direction of the dissolver.
Upon request we offer also PE Inliner solutions for the mixing vessels to save time for cleaning. By means of applying a vaccuum while the assembly of the liner it remain fixed at side wall of the vessel while stirring. Corresponding armatures for discharge are also available.
Basics of shear mixing
Basic ideas of shear mixing
The distinction between stirring and mixing is not entirely clear. If the liquid component, there is a stirring process.
Discontinuous / continuous shear mixers
The discontinuous machines predominate, which produce a batch determined by the machine size. Continuous Mixing Systems (continuous mixers) are mainly used for mixing low to medium viscositymedia; static mixers and continuous mixers can be mentioned as an example.
Dynamic / Static Mixers
Dynamic mixers are systems with moving mixing elements or moving containers. Static mixers are continuous systems in which fixed installations in a pipe or duct a mixture by exploiting the flow energy of the fluids (liquid / gas).
Kneader
If a highly viscous mix is additionally affected by normal forces during mixing deformed, this is called kneading. A planetary agitator can work as a kneader if appropriate stirring tools are used (e.g. planetary agitator as a double planetary system).
Homogenizer
The homogenizers are so-called sprocket dispersing machines, which consist of a rotor with high speed and a fixed stator; Both are slit. Rotor and stator often have several concentrically nested Sprockets.
High-pressure homogenizers, on the other hand, work without moving components; In their case, the fluid is forced through narrow holes under high pressure.
Basic stirring tasks
Homogenizing: In stirring technology, homogenization is the mixing of mixtures soluble liquids up to a certain degree of homogeneity (mixing quality) or the maintaining homogeneity for performing a reaction. The mixtures to be mixed liquids can differ in concentration, colour or concentration, for example.
Temperature: The time required for mixing is used as a mixing or mixing process.
Homogenization time:The emulsions consist of the continuous (contiguous) phase in the the disperse phase is distributed in the form of fine droplets and the emulsifier, which is attached to the of the phase interface.
Experience has shown that segregation take place after a very short time when oil is mixed with water. The remedy is so-called emulsifiers, which act as transfer stop between the two phases, f.e. shows the mode of action of emulsifiers. The fat-loving part (hydrophobic) feels inclined towards the oil or fat phase, the water-loving part (hydrophilic) of the water phase. The only one that acts at the phase boundary weakness emulsifier is the link between the two systems. The emulsifier is all the more effective the finer oil and water are mixed together.
Examples of emulsions in the food sector include:
Oil in water emulsions
- Dressings
- Mayonnaise
- Milk, yoghurt, cheese
- Cream
- Ice cream
Water in oil emulsions
- Butter
- Margarine
- Spreadable fats, spreads
In practice, you often have to deal with oil in water emulsions. What type of emulsion does not necessarily depend on the percentage of the two phases but rather on the type of emulsifier used.
For the emulsion build-up, water phase, oil phase and emulsifier are first mixed with the planetary or central agitator in the stirring vessel and a relatively unstable raw emulsion is created. After this pre-emulsification, an increased mechanical energy input must take place in order to have a stable fine emulsion at the end. Here to rotor-stator systems (homogenizers) are used, among other things. Due to the narrow shear gap between the rotor and stator, the shear gaps required for droplet crushing necessary high shear stresses.
Due to density differences, sedimentation or creaming can occur. In aggregation, droplets of the disperse phase are deposited on each other and of the coalescence, several small drops combine to form one large drop. At the end of these three mechanisms is the breakage of the emulsion, which means a phase separation.
Gas
The aim of gassing a liquid is to increase the phase interface between of the liquid and the gas. As a rule, the liquid is the continuous phase (= contiguous phase) and the gas the disperse phase (= distributed phase). Basically, a distinction is made between self-gassing and external fumigation. In the In practical application, the predominant external fumigation is used, for example, by a ring shower
the gas is fed into the stirring tank; the agitator must turn the gas flow into small bubbles and distribute evenly in the liquid.
Heat exchange
For many process engineering processes, controlled heat management is of the greatest importance meaning. Due to the unfavorable ratio of heat transfer area to container volume often only small amounts of heat can be transferred per unit of time. Heat transfer can be improved by a suitable agitator; it has the task of reducing the flow generated at the heat transfer surface (vessel wall) to influence the stirred material in such a way that the heat transfer coefficient and thus the heat transfer coefficient.
Cleaning
Production facilities must be carefully cleaned and disinfected. In the following, cleaning using the example of dairy technology. If milk comes into contact with surfaces of containers, pipelines and other process equipment that have not been properly cleaned, it becomes infected; Milk is an excellent breeding ground for microorganisms.
A distinction is made between physical and chemical cleanliness of a system, in which all dirt deposits and residues on the surface are removed and biological cleanliness, in which all living microorganisms are removed or killed. It is easier to achieve biological cleanliness if the surfaces have been physically and chemically cleaned beforehand.
Most cleaning processes can be divided into three phases:
- Detachment of dirt from the surface to be cleaned
- Dispersing of the dissolved dirt in the cleaning agent
- Keeping the dissolved dirt suspended in suspension.
In recent years, manual cleaning has been replaced by mechanical and, in many cases, with automated cleaning. This cleaning is called CIP cleaning known.
In this context, pigging technology must also be mentioned, with which, among other things, Highly viscous liquids and pasty media almost completely removed from piping systems can be removed. For this purpose, an approximately spherical body, the so-called pig, pressed through the piping system, e.g. with the help of compressed air. The newt pushes the product residues in the pipeline in front of it, which are of the system.
CIP cleaning
In CIP cleaning, the rinse water and detergent solutions circulate through tanks, pipelines and process lines without the need for manual cleaning. Dismantling of the process plant components is necessary. Due to a high flow rate of cleaning agent solutions in pipelines, heat exchangers, pumps, valves, mixers, etc. are installed on the surfaces of the equipment a high shear stress and thus a mechanical cleaning effect to loosen.